1. Field of the Invention
The present invention relates to an improved absorbable cap for bladder enlargement in patients with low compliance (low filling capacity) in the treatment and therapy of atrophied bladders, but also for the replacement of a vast portion of bladder following bilharzia.
2.Description of the Related Art
Patients with low compliance generally have an atrophied bladder whose volume is about 150-200 cc, much smaller than the volume of a healthy bladder which is normally around 400 cc. This entails, as is intuitive, serious problems for the patient.
Moreover low compliance is associated in general with the disorder of incontinence and of urine leakage when coughing or during effort.
In order to overcome these disadvantages surgical treatment is adopted which lies in the implanting, on the atrophied bladder, of a prosthesis of hemispherical or cap shape and internally hollow in order to increase the overall volume of the expanded bladder.
This prosthesis is generally made with the intestine tissue of the actual patient in order to have high compatibility, reduced rejection and reduced formation of the fibrous capsule.
However the tissue of the intestine does not always have the same mechanical properties as the tissue of the bladder, such as for example elasticity, nor the ability to assume stably a substantially hemisphere shape which is necessary in order to supply a constant volume of expansion of the bladder and maintain it as such.
To this end the Applicant has developed an absorbable domed cap, internally hollow, of textile in PGA and reinforced with strips of the same textile, which allows the technical problem described above to be solved. See patent application MI2011A000386.
However, following further tests, the Applicant has found that this cap very often tends to collapse during the growth of the neotissue after the implant, very probably due to the weight of the growing neotissue after the implant: this causes a smaller increase in volume compared to that supplied by a non-subsiding cap which maintains its round domed profile also under the weight of the growing neotissue. Moreover this known cap tends to create adherences inside the abdomen, in the implant point. See the test reproduced below.
WO2011/064110 describes a planar patch of textile in PGA with reinforcement strips made with the same textile in PGA, to be used for the reconstruction of a portion of bladder wall following a partial cystectomy.
This patch however, being made throughout with fibres of PGA homopolymer, has an absorption time of the order of 30 days, similar to the time of growth of bladder neotissue: this entails a decline in the mechanical properties during this period of absorption which consequently leads to the collapse of said patch inside the bladder under the weight of the new growing tissue, given the decreased rigidity and load-bearing capacity in said space of time, similar to what is described above.
US 2005/0113938 describes a biocompatible implant for the reconstruction of tissues, different from the bladder tissue, formed by a foam made up, among others, of PGA/PLA which is reinforced with textile or porous elements, formed, among others, by fibres of PGA/PLA.
This implant is however poorly suitable for a bladder enlargement in view of the high porosity, both of the foam and of the reinforcement elements, which, although on the one hand ensures the populating of the implant by the growing neotissue, on the other hand determines an undesirable leakage of urine from the bladder during the growth of the autologous neotissue.